The present invention relates to a picker for electronic components, more particularly for picking and subsequently testing the components including a feed rail for accommodating a plurality of components arranged juxtaposed in a row.
The picker may be employed in conjunction with electronic components of various kinds, more particularly integrated circuits.
One such picker is known from DE 35 39 973 A1. This known picker comprises a pivotable feed rail accommodating a row of components to be tested. The bottom-most component in each case is tested while still being within the feed rail, it resting thereby on a fixed support plate. On completion of testing the feed rail is pivoted, causing the bottom-most component to slide on the support plate. Provided in the pivoting direction of the feed rail is a spring-loaded retaining pin which penetrates an opening in the feed rail on pivoting and comes into contact with the second component In further pivoting the bottom-most component passes over the edge of the support plate and is output downwards into a further rail, The further components accommodated in the feed rail are arrested by the retaining pin. On pivoting return of the feed rail the retaining pin releases the retained component which slips downwards into the feed rail and comes to rest on the support plate. This second and all further components are tested the same as the first.
This known device works satisfactorily up to certain dimensions of the components to be tested. When picking and testing miniature components there is, however, the risk of contact errors, due to the components being located directly juxtaposed and still to be picked in contacting and testing. Furthermore, speedy picking and testing the components is not possible due to the mass requiring movement being very large.
It is thus the object of the present invention to provide a picker permitting speedy and reliable picking of even miniature components.
In accordance with the invention this object is achieved in the case of a picker of the aforementioned kind which additionally comprises a conveyor unit arranged at an exit opening of the feed rail and perpendicularly shiftable relative to the feed rail, a window suitable for receiving a single component of the plurality of components, the single component being shiftable together with the conveyor unit when received in the window, and an impact-controllable stop provided in the feed rail upstream of the conveyor unit for arresting components accomodated in the feed rail, wherein the spacing between the stop and an end of the feed rail facing the conveyor unit is substantially twice the overall length of a component.
The shiftable conveyor unit permits use of a fixed feed rail and a reduction in the mass moved. The size of the window in the conveyor unit ensures that only one component at a time can be received, thus achieving reliable picking without requiring any separate arresting means in the conveyor unit, i.e. there being no need for a power supply to the conveyor unit, thus achieving a simple and low-cost design. The impact controllable stop prevents the feed-through of further components onto the bottom-most component accommodated in the window of the conveyor unit, thus reducing the urging force so that the conveyor unit has facilitated movement to thus avoid damage to the components.
The spacing between the stop and the end of the feed rail facing the conveyor unit is substantially twice the overall length of a component, the stop thus parting two components earmarked for picking from the other components accommodated in the feed rail. The urging pressure on the bottom-most component is substantially reduced, but is still sufficient to ensure a reliable insertion into the window of the conveyor unit .
Advantageous further embodiments and aspects of the invention are also disclosed by this specification.
In one advantageous embodiment the conveyor unit is con figured for tolerance compensation higher on one side of the window than on the opposite side, i.e. the conveyor unit is thus configured stepped, the higher side being arranged facing away from the feed rail in the shifting direction. The lower side sweeps the guideway for the components configured in the feed rail in the shifting action of the conveyor unit. During this shifting action the subsequent component in each case is in contact with the surface of the lower side. This tolerance compensation ensures even in the case of fluctuating outer dimensions, especially when the overall length of the component fluctates, that a reliable shift of the conveyor unit is possible. As long as the overall length of the components is located within the side heights of the conveyor unit there is no restriction to the shifting action of the conveyor unit.
In another advantageous aspect a second conveyor unit having a window suitable for receiving a component is provided downstream of the first conveyor unit and capable of being travelled parallel to the first conveyor unit. This second conveyor unit receives a component already picked from the first conveyor unit. This component may then be put through the various steps in processing or testing without influencing the other components contained in the picker.
To advantage a contacting device is provided with which a component held in the second conveyor unit is connectable for testing. This contacting device permits more particularly checking the integrated electronic circuits contained in the component.
In accordance with another advantageous further embodiment a rail is provided offset from the feed rail between the first conveyor unit and the second conveyor unit. This rail causes the components to be guided between the first and second conveyor unit. Offsetting the rail from the feed rail prevents one or more components dropping directly through the window of the first conveyor unit into the rail, thus ensuring reliable picking.
To advantage the travel of the second conveyor unit is greater than the travel of the first conveyor unit. This greater travel permits removal of the picked component from the feed rail and from further components applied to the feed rail. Due to this arrangement a reliable large contacting/tester device may be employed.
In another advantageous further embodiment a ramp is provided along the travel of the second conveyor unit for aligning a component accommodated in the second conveyor unit. In the shifting action of the second conveyor unit the component comes into contact with the ramp by which it is oriented in a predetermined position, as a result of which accuracy in contacting and thus testing the component is even assured when the component is intially wrongly located in the second conveyor unit.
To advantage a discharge rail for receiving and guiding the picked components is provided downstream of the second conveyor unit, this discharge rail being in line with the feed rail. The discharge rail permits reliable component handling and guidance, more particularly in rejecting components on which testing the integrated electronic circuits failed to produce a satisfactory result. Arranging the discharge rail in line with the feed rail enables the components to be input and output in one and the same plane, thus simplifying the design of the picker as a whole and facilitating its integration into an existing host system.
Advantageously at least one photocell is provided for sequence control and sensing the presence of a component, this at least one photocell xe2x80x9cseeingxe2x80x9d whether a component has been positioned as intended or has left a predetermined position, thus enabling backups in the feed rail or a component jammed in the conveyor unit to be reliable detected and quickly remedied.
In another advantageous further embodiment each photocell is arranged on a fixed part of the picker, the moving parts, more particularly the conveyor units then requiring no power supply, thus enabling the design to be maintained, simple and rugged whilst involving low maintenance and costs.
In accordance with yet another advantageous aspect the feed rail comprises an upper part and a lower part, the spacing between upper part and lower part being variable by means of a signal-controllable positioner, more particularly a pneumatic positioner, thus enabling the guideway formed in the feed rail between upper part and lower part for the components to be varied as required, especially in enabling its headway to be reduced or increased so that any components having become snagged can thus become separated. This arrangement enables backups due to tilting or snagging between the components to be prevented or remedied. Making use of a pneumatic positioner eliminates any formation of magnetic fields or interference electrical fields which could otherwise detriment testing of the electronic components when using electrically actuated positioners.
In still another further embodiment one or more air nozzles are provided for conveying the components. When the feed rail is positioned perpendicularly or inclined the air nozzles are able to assist or, when so required, counteract movement in the conveying direction.